<template xmlns:v-touch="http://www.w3.org/1999/xhtml">
  <div>
    <div style="text-align: center;color: #FF5E3A;margin-top: 11px;margin-bottom: 24px;font-size: 16px">
      {{ numberValue }}.0</div>
    <div class="ruler " ref="testAA" style="border: 1px solid #B5C0CD;">
      <div class="main"
        :style="{ '-webkit-transform': 'translateX(' + mainValue + 'px)', 'width': getMainWidth + 'px', position: 'relative', left: '0px' }">
        <ul style="overflow: hidden;  -webkit-transform: translateX(45px);">
          <li v-touch:touchstart="onTouchStart" v-touch:touchmove="onTouchMove" v-touch:touchend="onTouchEnd"
            v-touch:touchcancel="onTouchEnd" v-for="(n, index) in itemCount" :key="n"><span class="num">{{ min + index * 5
              }} </span>
          </li>
        </ul>
      </div>
      <div class="arrow"></div>
    </div>
  </div>
</template>
<script>
export default {
  props: ["value", "min", "max", "onChange"],
  components: {},
  data: function () {
    return {
      mainValue: 0,
      end: 0,
      numberValue: this.value,
      start: 0,
      startX: 0,
      moveX: 0,
      X: 0,
      gap: this.value - this.min
    }
  },
  computed: {
    itemCount() {
      const num = this.max - this.min;
      let value = num / 5;
      return value + 1;
    },
    getMainWidth() {
      return ((this.max - this.min) / 5 + 2) * 104
    }
  },
  created() {

  },
  mounted() {
    this.calcInit(this.value);
  },
  methods: {

    calcInit(value) {
      let startValue = this.min - 5;
      let width = this.$refs.testAA.offsetWidth;

      let centerPX = width / 2 - 40;
      let offsetKe = centerPX / 104;
      while (offsetKe > 0) {
        if (offsetKe < 1) {
          startValue += offsetKe * 5;
        } else {
          startValue += 5
        }
        offsetKe--;
      }

      let offsetPx = (value - startValue) / 5;
      offsetPx = offsetPx * 105 - offsetPx;
      this.mainValue = -offsetPx;
    },
    onTouchStart(e) {
      const that = this;
      e.stopPropagation();
      that.start = 0;
      that.end = -((this.max - this.min) * 20.8);
      that.startX = e.changedTouches[0].pageX - that.mainValue;
    },
    onTouchMove(e) {
      e.preventDefault();
      const that = this;
      that.moveX = e.changedTouches[0].pageX;
      that.X = that.moveX - that.startX;

      if (that.X > 0) {
        var vv = that.mainValue;
        if (vv >= that.start) {
          that.start = that.X > that.start ? that.start : that.X;
          that.mainValue = that.start;
        } else {
          that.mainValue = that.X;
        }
      } else {
        var vv = that.mainValue;
        if (vv <= that.end) {
          that.end = that.X < that.end ? that.end : that.X;
          that.mainValue = that.end;
        } else {
          that.mainValue = that.X;
        }
      }

      let width = this.$refs.testAA.offsetWidth;
      let startValue = this.min - 5;
      let centerValue = startValue;

      let centerPX = width / 2 - 40;
      let offsetKe = centerPX / 104;
      while (offsetKe > 0) {
        if (offsetKe < 1) {
          centerValue += offsetKe * 5;
        } else {
          centerValue += 5
        }
        offsetKe--;
      }
      let a = Math.abs(that.mainValue) / 20.8;
      that.numberValue = Math.round(centerValue + a);
      if (that.numberValue >= that.max) {
        that.numberValue = that.max;
        that.calcInit(that.max);
        return;
      }
      if (that.numberValue <= that.min) {
        that.numberValue = that.min;
        that.calcInit(that.min);
        return;
      }
    },
    onTouchEnd(var1, var2) {
      this.onChange && this.onChange(this.numberValue);
      this.calcInit(this.numberValue);
    }
  }
}
</script>
<style>
ul,
li {
  list-style: none;
  padding: 0;
}

.ruler {
  height: 90px;
  overflow: hidden;
  position: relative;
  width: 100%;
  margin-left: auto;
  margin-right: auto;
  background-color: #F8FAFF;
}

.ruler li {
  float: left;
  width: 104px;
  height: 60px;
  background: url() left top no-repeat;
  background-size: 94px;
  padding-top: 30px;
  text-align: right;
  padding-left: 0;
}

.ruler li .num {
  display: inline-block;
  position: relative;
  margin-right: -6px;
}

.ruler .arrow {
  width: 0;
  height: 0;
  border: 8px solid transparent;
  border-top: 8px solid #ffa657;
  position: absolute;
  left: 50%;
  top: 0;
  margin-left: -8px;
}

.main li {
  background: url() left top no-repeat;
  background-size: 100px auto;
  color: #b5d0e1;
}
</style>